The present invention relates to the synthesis of olefins from ketones or aldehydes using bis(alkylchloroalumino)methane as an organoaluminum methylenating agent whereby the carbonyl oxygen atom of the ketone or aldehyde is replaced with a methylene group to form the corresponding olefin. 2. Description of the Prior Art
Conversion of a carbonyl function to a carbon-carbon double bond is a known industrial procedure. It is commonly achieved by use of phosphorus ylids in the Wittig reaction. Although such a reaction is general for both aldehydes and ketones, in certain instances poor yields of olefinic products are obtained when carbonyl compounds are attacked by the highly reactive bases used to generate phosphorus ylids. In view of the market potential for the reaction and certain disadvantages in regard to use of Wittig reagents, some other alternatives have been examined.
Gem-dimetallic derivatives, such as bis-halomagnesiomethane, have been proposed for use (F. Bertini et al., Tetrahedron 26, 1281, 1970) but such geminal dimagnesium compounds are difficult to make and are thus expensive.
Geminal dialuminum compounds, such as bis-dibromoaluminomethane, are more inexpensive to prepare but were found by A. Bongini et al. (J. of Organomet. Chem., 72 (1974) C4-C6 to be quite unreactive towards ketones and only moderately reactive with aldehydes.
Ashby et al. (J. of Organomet. Chem. 225 (1982) 71-85) utilized bis(diethylalumino)methane to ethylate 4-t-butylcyclohexanone. Ashby et al. observed 4-t-butyl-1-methylenecyclohexane in the product, but the relatively low yield (43%) would not justify use of bis(diethylalumino)methane as a Wittig reagent replacement.